The present invention relates to a crankshaft, and more particularly to a bicycle crankshaft assembly in which a crankshaft is properly supported by a shockproof ring within a frame tube.
As shown in FIG. 1, a bicycle crank axle set 1A of the prior art comprises an axle 2A, a sleeve 3A fastened with one end of the axle 2A, and a threaded casing 4A fastened with the other end of the axle 2A. The crank axle set 1A is fastened with a bicycle frame tube 5A which is provided in one end with inner threads 6A, and in other end with inner threads 7A. The threaded casing 4A is made by punching and therefore is not cost-effective. The bicycle frame tube 5A is provided in both ends thereof with inner threads 6A and 7A, which are also not cost-effective. In addition to the high production cost of the crank axle set 1A and the frame tube 5A, the fastening of the crank axle set 1A with the frame tube 5A is not reliable in view of the fact that the fastening mechanism is attained by the threads, which are susceptible to wear or damage. As a result, the axle 2A of the bicycle axle set 1A is apt to become loose.
It is an objective of this invention to provide a bicycle crankshaft assembly configured by simple but reliable structure.
In order to achieve the objective set forth, a bicycle crankshaft assembly in accordance with the present invention comprises a frame tube having first and second end portions and defining a passage extending between the end portions. The first end portion define a first opening, and the second end portion define a second opening different to the first opening. An axle is securely assembled into the passage from the second end portion and the axle includes a bushing with a crankshaft rotationally supported therein. The crankshaft includes first and second coupling portions extending over the first and second openings of the first and second end portions of the frame tube. Wherein the first opening is dimensioned such that a first end of the bushing is limited from extending therethrough.
The features of the present invention will be more readily understood upon a thoughtful deliberation of the following detailed description of a preferred embodiment of the present invention with reference to the accompanying drawings.